Contact

Barry Nehring, a Colorado Division of Wildlife biologist, stands in front of the Gunnison Gorge, where whirling disease nearly wiped out a legendary rainbow trout fishery.  Photo by Anders Halverson
A Colorado Division of Wildlife crew electrofishing in the Gunnison Gorge. Some of the crew hold wands that send out a small electric shock, while others wait to net the stunned fish.  Photo by Anders Halverson
A Colorado Division of Wildlife crew electrofishing in the Gunnison Gorge in September 2006. Some of the crew hold wands that send out a small electric shock, while others wait to net the stunned fish. Photo by Anders Halverson
A Colorado Division of Wildlife crew electrofishing in the Gunnison Gorge. For bigger fish, a boat like this is used.  Photo by Anders Halverson
Colorado Division of Wildlife biologists examine a stunned rainbow in the Gunnison Gorge to gather population data and evidence of whirling disease. The department released a strain of rainbows resistant to whirling disease into the river the previous year, this was probably one of them.  Photo by Anders Halverson
Most infected rainbow trout die from whirling disease at a very young age. Those that do survive usually have deformed skeletons and skulls, bulging eyes, and black tails, like the ones pictured above.  Photo by Sascha L. Hallett
Under a microscope, a Myxobolus cerebralis triactinomyxon looks like a grappling hook. At this stage, the parasite is ready to attach to a fish. When it does, three coiled springs in the tip (the dark portion on the right) shoot into the skin, providing a secure entrance route for the germ capsule.  Photo by Vicki Blazer, U.S. Geological Survey
The whirling disease parasite, Myxobolus cerebralis, forms small spores like this one, photographed with an electron microscope. The spores remain viable for dozens of years in the mud, until they are eaten by a small worm known as Tubifex tubifex. When the worms die, they release another phase of the parasite known as a triactinomyxon (TAM) that is ready to infect another fish and complete the life cycle.  Photo by Ronald P. Hedrick
With places like this, is it any wonder the high Sierra lakes are so popular with fishermen?  Photo by Anders Halverson
Biologist Roland Knapp examines invertebrates he has sampled from a Sierra lake in July, 2006. Knapp has been studying the effects of fish removal on other inhabitants of such lakes including amphibians and invertebrates like these.  Photo by Anders Halverson
Seasonal employees of the California Department of Fish and Game and the U.S. Forest Service remove fish from gillnets in a high Sierra lake.  Photo by Anders Halverson
A seasonal employee of the U.S. Forest Service removes a dead rainbow trout from a gillnet in a Sierra Nevada lake in the fall of 2006.  Photo by Anders Halverson
Mountain yellow-legged frogs like this one have been declining due at least in part to fish stocking in the Sierra Nevada.  Photo by Jason Kling (U.S. Forest Service)
A view of the Sierra Nevada from Fish Slough, where the last population of Owens pupfish were discovered by Phil Pister, Robert Miller, and Carl Hubbs in 1964.  Photo by Anders Halverson

Follow andershalverson on Twitter